Q&A - PSLE Math

[MathIzzzFun]

buggy:

Hi all,


Need help in the following questions for my child. Thanks in advance for any help

Q2) Gina had a box of RED, BLUE and GREEN counters. The ratio of RED counters to BLUE counters was 5:2. The ratio of BLUE counters to GREEN counters was 3:5.
(a) What was the ratio of RED counters to BLUE counters to GREEN counters? - my kiddo seems to know how to do this
(b) After Gina took out 126 RED counters from the box, 1/3 of the remaining counters were RED. How many counters were left in the box?

Hi

Q2.
Red : Blue --> 5 : 2
Blue : Green --> 3 : 5
Red : Blue : Green --> 15 : 6 : 10

Red : Blue+Green --> 15u : 6u+ 10u = 15u : 16u
After 126 Red removed, counters left =
Red : Blue + Green --> 1 : 2 = 8u : 16u

so, 7u --> 126
1u --> 18
Number of counters left --> (8 + 16)x 18 = 432

cheers.

[MathIzzzFun]

buggy:

Hi all,


Need help in the following questions for my child. Thanks in advance for any help



Q3) The ratio of the number of beads Kenny has to the number of beads Sarah is 7:5. When Sarah gives 48 beads to Kenny, she has 1/3 of the number of beads Kenny has.
(a) How many beads does Kenny have after receiving the beads from Sarah?
(b) How many beads must Kenny give back to Sarah so that she will have 5 times as many beads as him?

Hi
Since the total number of beads remain the same, the total ratio parts must be the same :
At first, Kenny : Sarah --> 7u:5u (12u total)
After transfer, Kenny : Sarah --> 3:1 --> 9u : 3u (12u total)

2u --> 48, 1u --> 24

9 x 24 = 216 -- Kenny has 216 beads after transfer.

b)
Kenny : Sarah --> 1 : 5 --> 2u : 10u
9u - 2u = 7u --> 7 x 24 = 168
Kenny needs to give 168 beads to Sarah.

cheers.

[buggy]

MathIzzzFun:

Abel --> 12u...
Sherrie --> 12u...

Hi there,

Thanks!

I too thought it would involve breaking up the models into x units that are divisible by the fractions, i.e. 1/6, 1/4. But I struggled to find these concepts in the books :stupid: - is this correct or would you be able to elaborate a little on the concept?

[peggy]

tianzhu:

peggy:

Thanks, Tianzhu.

But any possibility of a mode. Think my DS can digest better with it.

Sorry to trouble you.

Hi

Hope this helps.

Best wishes.

http://farm8.staticflickr.com/7243/6966119100_e47f2d8176_z.jpg\">

Hi Tianzhu,

Thank you !!

Have a nice day !

Peggy

[MathIzzzFun]

buggy:

MathIzzzFun:

Abel --> 12u...
Sherrie --> 12u...

Hi there,

Thanks!

I too thought it would involve breaking up the models into x units that are divisible by the fractions, i.e. 1/6, 1/4. But I struggled to find these concepts in the books :stupid: - is this correct or would you be able to elaborate a little on the concept?

Hi
concept is the same as adding/subtracting fractions --> find the common denominator. In this case, find lowest common factor ie 12.

cheers.

[buggy]

MathIzzzFun:

buggy:

[quote=\"MathIzzzFun\"]
Abel --> 12u...
Sherrie --> 12u...

Hi there,

Thanks!

I too thought it would involve breaking up the models into x units that are divisible by the fractions, i.e. 1/6, 1/4. But I struggled to find these concepts in the books :stupid: - is this correct or would you be able to elaborate a little on the concept?

Hi
concept is the same as adding/subtracting fractions --> find the common denominator. In this case, find lowest common factor ie 12.

cheers.[/quote]Hi,

Thanks! Will look through the rest!

[peggy]

Please help with this.


Four children Min, Nathan, Tom and Caleb each have some savings. The amount of money Nathan has is 1/3 of the total amount of money Tome and Caleb have. The amount of money Tom has is 1/4 of the total amount of money Nathan and Caleb have. The amount of money Min has is 1/5 of the total amount of money Nathan, Tom and Caleb have. If Caleb saves $1035 how much do the four children have altogether ?

I use ratio and ended with the following :

N : T + C ----- 1 : 3 ----- 5 : 15 = 20u
T : N + C ------1 : 4 ------ 4 : 16 = 20u
M : N + C + T —1 : 5 ----- 4 : 20

Nathan - 5u
Tom - 4u
Min - 4u
Caleb - 11u

11u = 1035
1u = 94.0909

After getting the decimal, knew something was wrong. Please advise what went wrong.

thank you.

[Michaelia0816]

It was not 11u at all!

[tianzhu]

peggy:

Please help with this.


Four children Min, Nathan, Tom and Caleb each have some savings. The amount of money Nathan has is 1/3 of the total amount of money Tome and Caleb have. The amount of money Tom has is 1/4 of the total amount of money Nathan and Caleb have. The amount of money Min has is 1/5 of the total amount of money Nathan, Tom and Caleb have. If Caleb saves $1035 how much do the four children have altogether ?

I use ratio and ended with the following :

N : T + C ----- 1 : 3 ----- 5 : 15 = 20u
T : N + C ------1 : 4 ------ 4 : 16 = 20u
M : N + C + T ---1 : 5 ----- 4 : 20

Nathan - 5u
Tom - 4u
Min - 4u
Caleb - 11u

11u = 1035
1u = 94.0909

After getting the decimal, knew something was wrong. Please advise what went wrong.

thank you.

Hi

Please check your question.

A similar question was discussed before.

Four children Min, Nat, Tom and Caleb each have savings. The amount of money Nat has is 1/3 of the total amount of money Tom , Min and Caleb have. The amount of money Tom has is 1/4 of the total amount of money Nat , Min And Caleb have. The amount of money Min has is 1/5 of the total amount of Nat. Tom and Caleb have. If Caleb saves $1035 . How much do the four children have altogether?

The total amount of money in the three scenarios is the same. Make the total number of units the same.

A common multiple of 4, 5 and 6 is 60.

Nat : (Tom + Min + Caleb) ------ 1:3 ((4) ------ 15:45 (60)
Tom : (Nat + Min + Caleb) ------ 1:4 (5) ------ 12:48 (60)
Min : (Nat + Tom + Caleb) ------ 1:5 (6) ------ 10:50 (60)

Nat ------ 15 units
Tom ------ 12 units
Min ------- 10 units
Caleb ------ 23 units

23 units ------ 1035
1 unit ------ 45

60*45 ------ 2700

Best wishes

[peggy]

Hi Tianzhu,


I recheck the question and is exactly what I had posted. Really don’t why.
Anyway, thanks so much for pointing the error.

Question solved.

Thank you.